Poolman B, Glaasker E
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
Mol Microbiol. 1998 Jul;29(2):397-407. doi: 10.1046/j.1365-2958.1998.00875.x.
In their natural habitats, microorganisms are often exposed to osmolality changes in the environment. The osmotic stress must be sensed and converted into an activity change of specific enzymes and transport proteins and/or it must trigger their synthesis such that the osmotic imbalance can be rapidly restored. On the basis of the available literature, we conclude that representative gram-negative and gram-positive bacteria use different strategies to respond to osmotic stress. The main focus of this paper is on the initial response of bacteria to hyper- and hypo-osmotic conditions, and in particular the osmosensing devices that allow the cell to rapidly activate and/or to synthesize the transport systems necessary for uptake and excretion of compatible solutes. The experimental data allow us to discriminate the transport systems by the physicochemical parameter that is sensed, which can be a change in external osmotic pressure, turgor pressure, membrane strain, internal osmolality and/or concentration of specific signal molecule. We also evaluate the molecular basis for osmosensing by reviewing the unique structural features of known osmoregulated transport systems.
在其自然栖息地中，微生物常常会面临环境渗透压的变化。必须感知这种渗透胁迫，并将其转化为特定酶和转运蛋白活性的改变，和/或触发它们的合成，以便迅速恢复渗透失衡。基于现有文献，我们得出结论，代表性的革兰氏阴性菌和革兰氏阳性菌采用不同策略应对渗透胁迫。本文的主要重点是细菌对高渗和低渗条件的初始反应，特别是允许细胞快速激活和/或合成摄取和排泄相容性溶质所需转运系统的渗透感应装置。实验数据使我们能够根据所感知的物理化学参数来区分转运系统，该参数可以是外部渗透压、膨压、膜应变、内部渗透压和/或特定信号分子浓度的变化。我们还通过回顾已知的渗透调节转运系统的独特结构特征来评估渗透感应的分子基础。
